I'm a student. At the end of the first year of painting we were given the choice of a texture project or doing a baroque master. I chose the master.
But I have notes given to us by the teacher and dug them out. I don't have anything on oxides and bitumen, (although I remember seeing it drizzled into shellac while both are 'wet', I haven't got around to trying it. And dropping pva into it gives a nice effect, it separates in the mix. Needs good ventilation and to lay flat for days, maybe longer. One of my classmates tried it at home but she said it wasn't very successful as it was taking too long to dry. So try a small tester in case it doesn't work!)
There is also a mention of bitumen as a stain with a texture made of sand & glue if you want that. Some of my current classmates have experimented with it but I think they've used it like a paint.